Loud speaker



p a. A. ENGHOILM 1,972,927

' LOUD SPEAKER filed July 30, 1932 7 v 3mm 13M aw Patented Sept- 1934 i UNITED STATES PATENT orncr;

LOUD SPEAKER Bernard A. Engholm, Lakewood, Ohio, allignor to The Bola Company, Cleveland, Ohio, a corporation of Ohio Application July 30, 1932, Serial No. 628,105 3 Claims. (Cl. 179146) This invention relates to radio loud speakers In the preferred arrangement, the rearward and particularly to those, which are intended for edge 19 of the outer housing terminates in a. use in motor vehicle installation. One iorm of plane, which is offset from a plane which passes loud speaker mounting, which has been found to through the rearward end of the field coil shell.

g be satisfactory for this purpose comprises a A single bolt 21 which is shown as being rigidly 60 single-bolt, which is carried by the field coil and fastened to the field coil core projects rearwardly which extends rearwardly from the field coil shellfrom the shell and extends through the dash and supports the speaker on the dash board. In board 22 and operates to hold the speaker in such cases, the speaker housing embodies a hollow operative position thereon.

member which is fastened to the diaphragm To close the back of the speaker housing, I 65 housing at the forward portion thereof, and adprovide a closure 25 which is shown as having jacent the clamping ring, which holds the rim a frustro-conical body portion, and as having a of the diaphragm in place. It is desirable thereradially extending portion 2'! adjacent the apex fore, to close the back of the speaker housing end thereof. The base 26 of the closure fits and at the same time to support it so as to mainsnugly against the shoulder 18 while the portion 70 tain it in operative condition notwithstanding the 27 is provided with an opening through which fact that it may be subjected to excessive vibrathe bolt 21 is passed. Thus when the nut 28 is tion during use. The practice heretofore has drawn up tightly, the closure is rigidly held been to extend the speaker housing back to the against the dash board and the speaker housing end of the field coil shell and to close the back is rigidly held in turn by contact with the 010- "[5 with a float cardboard disc which has an opening sure. 4 through which the mounting bolt extends. To An advantageof my invention is the fact allow free movement of air however, in back of that the back of the speaker may be closed the diaphragm, it has been necessary to provide, without the necessity for using a spacing block openings in the disc and then to utilize a wooden and without the necessity for fastening the clogo spacer between the disc and the dash board to sure to'the speaker housing. Thus the speaker permit the free circulation of air behind the a be q y a t ed 101' S rv c Wo k and speaker. Furthermore, to obtain suflicient rigidwhen n u a b dl 18 d Y in p s tion ity, it has been necessary to attach the outer 8 1 h dashboard y a 1 818 b lt.

30 edge of the disc to the casing. I therefore as An object of my invention-is to provide a con- 1. In wmb n tion, a support having a penstruction, which will achieve the desired closing ing therein, a d speaker having a field coil of the back of the speaker housing in a satisfac- .shell disposed on one side of the support and tory and eflicient manner and which is well in c o e p x y thereto. a d aph agm asso- I adapted for use in connection with the single bolt elated with the Shell, 8 1101181118 encloflinfl th 90 mgunting of l d speakers, 4 speaker and extending backwardly toward the Referring now to the drawing, the figure shows support and terminating o t thereof. the a. vertical section through aloud speaker embodyhousing having su n i lly uniform cross-secing my invention. tional area throughout its length, a frusto-con- 40 I have shown my invention in connection with ical closure for the back of the housing, the base as an electrodynamic speaker having a field coil 10, 01 said closure being in 01058 fi n n a em nt ashell 11 therefor, a diaphragm 12, a diaphragm with the W811 0f the housing d having an housing or support 13, and an outer housing 14. opening adiacent the a x p t on thereof, a The outer housing is shown as a hollow member, Single boll; Projecting fl m the h ll which has an intumed flange 15 at the forward and extending throu h, the opening in the no edge thereof which is fastened to an outwardly D011? and threaded means 0n the bolt lockextending flange 16 on the housing 13. The rim s the shell and closure to the supp rt oi the diaphragm is then preferably fastened be- In combination. fl pp r 1 nd sp ak r tween these two flanges. Where metal is used comprising a fieldcoil shell. di p a m, a

for making the outer housing, I prefer to insert a inner housing associated therewiflt the inner 105 sleeve of sound absorbing material, such as cardu ng being mounted P the Shell a d exboard 17 and to terminate at the rearward end tending aw y from the PD m Outer ousof the sleeve short of the rearward edge of the ing having an inturned flange and having subhousing 14. This provides a shoulder 18 for restantially uniform cross-sectional area through- 55 ceiving the rim of the closure 25. out its length, means extending through the flange for locking the outer housing and diaphragm to the inner housing, whereby the outer housing is supported only at the diaphragm end thereof, a closure for the back of the outer housing, said closure comprising a irusto-conical member having a close fitting engagement with the outer wall of the housing, and the apex end of said closure being disposed between the shell and the support. and a bolt carried by the shell and extending through the support, said bolt operating to lock the speaker to the support and to hold the closure in locked position'with reference to the shell.

to the housing, 

